Hydrogen abstraction kinetics and crystallization in low temperature plasma deposition of silicon

Exposing a plasma deposited hydrogenated silicon layer to atomic hydrogen results in hydrogen removal from the silicon/hydrogen surface and a net reduction in the total hydrogen content in the layer. For deposition at low temperature, the crystallization fraction corresponds directly with the extent of hydrogen removal. Silicon films deposited using alternating deposition and hydrogen (or deuterium) plasma exposure are characterized by transmission infrared spectroscopy and Raman spectroscopy. Using mass spectroscopy, hydrogen abstraction and etching are observed and identified as important pathways for hydrogen removal at substrate temperatures between 25 degrees C and 300 degrees C. Moreover, the hydrogen abstraction kinetics show that the reaction is first order with an activation barrier of -0.4+/-1 kcal/mol, consistent with a spontaneous Eley-Rideal abstraction process. Energy barrier values are supported by ab initio calculations. (C) 1998 American Institute of Physics.